chain_mode.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*******************************************************************************
  3  Specialised functions for managing Chained mode
  4
  5  Copyright(C) 2011  STMicroelectronics Ltd
  6
  7  It defines all the functions used to handle the normal/enhanced
  8  descriptors in case of the DMA is configured to work in chained or
  9  in ring mode.
 10
 11
 12  Author: Giuseppe Cavallaro <peppe.cavallaro@st.com>
 13*******************************************************************************/
 14
 15#include "stmmac.h"
 16
 17static int jumbo_frm(struct stmmac_tx_queue *tx_q, struct sk_buff *skb,
 18		     int csum)
 19{
 20	unsigned int nopaged_len = skb_headlen(skb);
 21	struct stmmac_priv *priv = tx_q->priv_data;
 22	unsigned int entry = tx_q->cur_tx;
 23	unsigned int bmax, buf_len, des2;
 24	unsigned int i = 1, len;
 25	struct dma_desc *desc;
 26
 27	desc = tx_q->dma_tx + entry;
 28
 29	if (priv->plat->enh_desc)
 30		bmax = BUF_SIZE_8KiB;
 31	else
 32		bmax = BUF_SIZE_2KiB;
 33
 34	buf_len = min_t(unsigned int, nopaged_len, bmax);
 35	len = nopaged_len - buf_len;
 36
 37	des2 = dma_map_single(priv->device, skb->data,
 38			      buf_len, DMA_TO_DEVICE);
 39	desc->des2 = cpu_to_le32(des2);
 40	if (dma_mapping_error(priv->device, des2))
 41		return -1;
 42	tx_q->tx_skbuff_dma[entry].buf = des2;
 43	tx_q->tx_skbuff_dma[entry].len = buf_len;
 44	/* do not close the descriptor and do not set own bit */
 45	stmmac_prepare_tx_desc(priv, desc, 1, buf_len, csum, STMMAC_CHAIN_MODE,
 46			0, false, skb->len);
 47
 48	while (len != 0) {
 49		tx_q->tx_skbuff[entry] = NULL;
 50		entry = STMMAC_GET_ENTRY(entry, priv->dma_conf.dma_tx_size);
 51		desc = tx_q->dma_tx + entry;
 52
 53		if (len > bmax) {
 54			des2 = dma_map_single(priv->device,
 55					      (skb->data + bmax * i),
 56					      bmax, DMA_TO_DEVICE);
 57			desc->des2 = cpu_to_le32(des2);
 58			if (dma_mapping_error(priv->device, des2))
 59				return -1;
 60			tx_q->tx_skbuff_dma[entry].buf = des2;
 61			tx_q->tx_skbuff_dma[entry].len = bmax;
 62			stmmac_prepare_tx_desc(priv, desc, 0, bmax, csum,
 63					STMMAC_CHAIN_MODE, 1, false, skb->len);
 64			len -= bmax;
 65			i++;
 66		} else {
 67			des2 = dma_map_single(priv->device,
 68					      (skb->data + bmax * i), len,
 69					      DMA_TO_DEVICE);
 70			desc->des2 = cpu_to_le32(des2);
 71			if (dma_mapping_error(priv->device, des2))
 72				return -1;
 73			tx_q->tx_skbuff_dma[entry].buf = des2;
 74			tx_q->tx_skbuff_dma[entry].len = len;
 75			/* last descriptor can be set now */
 76			stmmac_prepare_tx_desc(priv, desc, 0, len, csum,
 77					STMMAC_CHAIN_MODE, 1, true, skb->len);
 78			len = 0;
 79		}
 80	}
 81
 82	tx_q->cur_tx = entry;
 83
 84	return entry;
 85}
 86
 87static bool is_jumbo_frm(unsigned int len, bool enh_desc)
 88{
 89	bool ret = false;
 90
 91	if ((enh_desc && (len > BUF_SIZE_8KiB)) ||
 92	    (!enh_desc && (len > BUF_SIZE_2KiB)))
 93		ret = true;
 94
 95	return ret;
 96}
 97
 98static void init_dma_chain(void *des, dma_addr_t phy_addr,
 99				  unsigned int size, unsigned int extend_desc)
100{
101	/*
102	 * In chained mode the des3 points to the next element in the ring.
103	 * The latest element has to point to the head.
104	 */
105	int i;
106	dma_addr_t dma_phy = phy_addr;
107
108	if (extend_desc) {
109		struct dma_extended_desc *p = (struct dma_extended_desc *)des;
110		for (i = 0; i < (size - 1); i++) {
111			dma_phy += sizeof(struct dma_extended_desc);
112			p->basic.des3 = cpu_to_le32((unsigned int)dma_phy);
113			p++;
114		}
115		p->basic.des3 = cpu_to_le32((unsigned int)phy_addr);
116
117	} else {
118		struct dma_desc *p = (struct dma_desc *)des;
119		for (i = 0; i < (size - 1); i++) {
120			dma_phy += sizeof(struct dma_desc);
121			p->des3 = cpu_to_le32((unsigned int)dma_phy);
122			p++;
123		}
124		p->des3 = cpu_to_le32((unsigned int)phy_addr);
125	}
126}
127
128static void refill_desc3(struct stmmac_rx_queue *rx_q, struct dma_desc *p)
129{
130	struct stmmac_priv *priv = rx_q->priv_data;
131
132	if (priv->hwts_rx_en && !priv->extend_desc)
133		/* NOTE: Device will overwrite des3 with timestamp value if
134		 * 1588-2002 time stamping is enabled, hence reinitialize it
135		 * to keep explicit chaining in the descriptor.
136		 */
137		p->des3 = cpu_to_le32((unsigned int)(rx_q->dma_rx_phy +
138				      (((rx_q->dirty_rx) + 1) %
139				       priv->dma_conf.dma_rx_size) *
140				      sizeof(struct dma_desc)));
141}
142
143static void clean_desc3(struct stmmac_tx_queue *tx_q, struct dma_desc *p)
144{
145	struct stmmac_priv *priv = tx_q->priv_data;
146	unsigned int entry = tx_q->dirty_tx;
147
148	if (tx_q->tx_skbuff_dma[entry].last_segment && !priv->extend_desc &&
149	    priv->hwts_tx_en)
150		/* NOTE: Device will overwrite des3 with timestamp value if
151		 * 1588-2002 time stamping is enabled, hence reinitialize it
152		 * to keep explicit chaining in the descriptor.
153		 */
154		p->des3 = cpu_to_le32((unsigned int)((tx_q->dma_tx_phy +
155				      ((tx_q->dirty_tx + 1) %
156				       priv->dma_conf.dma_tx_size))
157				      * sizeof(struct dma_desc)));
158}
159
160const struct stmmac_mode_ops chain_mode_ops = {
161	.init = init_dma_chain,
162	.is_jumbo_frm = is_jumbo_frm,
163	.jumbo_frm = jumbo_frm,
164	.refill_desc3 = refill_desc3,
165	.clean_desc3 = clean_desc3,
166};